问题
I have a server/client application which works for a write from client to a read at server.
Inside the startHandlig function in the server code, if I comment async_connect_1 and the return after it, then it works fine which involves sync write function.
I added async_connect_1 function inside Service() class to asynchronously read from the socket.
This function is called when a client connects to the server and this function returns immediately.
I expect the callback function corresponding to async_read to be called, but that is not happening...
I'm stuck at this since a long time.. Appreciate help on this...
Server Code
#include <boost/asio.hpp>
#include <boost/archive/text_iarchive.hpp>
#include <boost/archive/text_oarchive.hpp>
#include <boost/bind.hpp>
#include <boost/serialization/vector.hpp>
#include <boost/tuple/tuple.hpp>
#include <thread>
#include <atomic>
#include <memory>
#include <iostream>
#include "../stocks.hpp"
using namespace boost;
class Service {
public:
Service(){}
void StartHandligClient(
std::shared_ptr<asio::ip::tcp::socket> sock) {
read_async_1(sock);
return;
std::thread th(([this, sock]() {
HandleClient(sock);
}));
std::cout << "Detached \n";
th.detach();
}
private:
void read_async_1(std::shared_ptr<asio::ip::tcp::socket> sock)
{
if(!(*sock.get()).is_open())
{
std::cout << getpid() << " : Socket closed in sync_read \n" << std::flush;
return ;
}
std::cout << "haha_1\n" << std::flush;
boost::asio::async_read( (*sock.get()), boost::asio::buffer(inbound_header_),
[this](boost::system::error_code ec,
size_t bytesRead)
{
std::cout << "haha_2\n" << std::flush;
if (!ec)
{
int headerBytesReceived = bytesRead;
std::cout << "\n\n headerBytesReceived : " << headerBytesReceived << "\n" << std::flush ;
// this->async_read(sock);
}
else
{
// Terminate connection ?
if(ec == boost::asio::error::eof)
{
std::cout << getpid() << " : ** sync_read : Connection lost : boost::asio::error::eof ** \n";
}
std::cout << "Error occured in sync_read! Error code = " << ec.value() << ". Message: " << ec.message() << "\n" << std::flush;
return ;
}
return ;
}
);
std::cout << getpid() << " : final return from async_read \n" << std::flush;
return ;
}
void HandleClient(std::shared_ptr<asio::ip::tcp::socket> sock) {
while(1)
{
try {
// asio::streambuf request;
// asio::read_until(*sock.get(), request, '\n');
int headerBytesReceived = asio::read( *sock.get(), boost::asio::buffer(inbound_header_) );
std::cout << "headerBytesReceived : " << headerBytesReceived << "\n" << std::flush;
// Determine the length of the serialized data.
std::istringstream is(std::string(inbound_header_, header_length));
std::cout << "is : " << is.str() << ", inbound_header_ : " << inbound_header_ << "\n";
std::size_t inbound_data_size = 0;
if (!(is >> std::hex >> inbound_data_size))
{
// Header doesn't seem to be valid. Inform the caller.
// boost::system::error_code error(boost::asio::error::invalid_argument);
// boost::get<0>(handler)(error);
std::cout << "RET-1 \n";
return;
}
std::cout << "inbound_data_size : " << inbound_data_size << "\n" << std::flush;
// Start an asynchronous call to receive the data.
inbound_data_.resize(inbound_data_size);
std::cout << "inbound_data_.size() : " << inbound_data_.size() << "\n" << std::flush;
int bytesReceived = asio::read( *sock.get(), boost::asio::buffer(inbound_data_) );
std::string archive_data(&inbound_data_[0], inbound_data_.size());
std::istringstream archive_stream(archive_data);
boost::archive::text_iarchive archive(archive_stream);
archive >> stocks_;
std::cout << "bytesReceived : " << bytesReceived << " , stocks_.size() : " << stocks_.size() << "\n";
// Print out the data that was received.
for (std::size_t i = 0; i < stocks_.size(); ++i)
{
std::cout << "Stock number " << i << "\n";
std::cout << " code: " << stocks_[i].code << "\n";
std::cout << " name: " << stocks_[i].name << "\n";
std::cout << " open_price: " << stocks_[i].open_price << "\n";
std::cout << " high_price: " << stocks_[i].high_price << "\n";
std::cout << " low_price: " << stocks_[i].low_price << "\n";
std::cout << " last_price: " << stocks_[i].last_price << "\n";
std::cout << " buy_price: " << stocks_[i].buy_price << "\n";
std::cout << " buy_quantity: " << stocks_[i].buy_quantity << "\n";
std::cout << " sell_price: " << stocks_[i].sell_price << "\n";
std::cout << " sell_quantity: " << stocks_[i].sell_quantity << "\n";
}
}
catch (system::system_error &e)
{
boost::system::error_code ec = e.code();
if(ec == boost::asio::error::eof)
{
std::cout << "EOF Error \n";
}
std::cout << "Server Error occured! Error code = "
<< e.code() << ". Message: "
<< e.what() << "\n";
break;
}
}
// Clean-up.
delete this;
}
/// The size of a fixed length header.
enum { header_length = 8 };
/// Holds an outbound header.
std::string outbound_header_;
/// Holds the outbound data.
std::string outbound_data_;
/// Holds an inbound header.
char inbound_header_[header_length];
/// Holds the inbound data.
std::vector<char> inbound_data_;
std::vector<stock> stocks_;
};
class Acceptor {
public:
Acceptor(asio::io_service& ios, unsigned short port_num) :
m_ios(ios),
m_acceptor(m_ios,
asio::ip::tcp::endpoint(
asio::ip::address_v4::any(),
port_num))
{
m_acceptor.listen();
}
void Accept() {
std::cout << "Server Accept() \n" << std::flush;
std::shared_ptr<asio::ip::tcp::socket>
sock(new asio::ip::tcp::socket(m_ios));
m_acceptor.accept(*sock.get());
(new Service)->StartHandligClient(sock);
}
private:
asio::io_service& m_ios;
asio::ip::tcp::acceptor m_acceptor;
};
class Server {
public:
Server() : m_stop(false) {}
void Start(unsigned short port_num) {
m_thread.reset(new std::thread([this, port_num]() {
Run(port_num);
}));
}
void Stop() {
m_stop.store(true);
m_thread->join();
}
private:
void Run(unsigned short port_num) {
Acceptor acc(m_ios, port_num);
while (!m_stop.load()) {
std::cout << "Server accept\n" << std::flush;
acc.Accept();
}
}
std::unique_ptr<std::thread> m_thread;
std::atomic<bool> m_stop;
asio::io_service m_ios;
};
int main()
{
unsigned short port_num = 3333;
try {
Server srv;
srv.Start(port_num);
std::this_thread::sleep_for(std::chrono::seconds(100));
std::cout << "Stopping server \n";
srv.Stop();
}
catch (system::system_error &e) {
std::cout << "Error occured! Error code = "
<< e.code() << ". Message: "
<< e.what();
}
return 0;
}
Client Code
#include <boost/asio.hpp>
#include <boost/archive/text_iarchive.hpp>
#include <boost/archive/text_oarchive.hpp>
#include <boost/bind.hpp>
#include <boost/serialization/vector.hpp>
#include <iostream>
#include "../stocks.hpp"
using namespace boost;
class SyncTCPClient {
public:
SyncTCPClient(const std::string& raw_ip_address,
unsigned short port_num) :
m_ep(asio::ip::address::from_string(raw_ip_address),
port_num),
m_sock(m_ios) {
m_sock.open(m_ep.protocol());
}
void connect() {
m_sock.connect(m_ep);
}
void close() {
m_sock.shutdown(
boost::asio::ip::tcp::socket::shutdown_both);
m_sock.close();
}
std::string emulateLongComputationOp(
unsigned int duration_sec) {
std::string request = "EMULATE_LONG_COMP_OP "
+ std::to_string(duration_sec)
+ "\n";
sendRequest(request);
return receiveResponse();
};
private:
void sendRequest(const std::string& request) {
std::vector<stock> stocks_;
// Create the data to be sent to each client.
stock s;
s.code = "ABC";
s.name = "A Big Company";
s.open_price = 4.56;
s.high_price = 5.12;
s.low_price = 4.33;
s.last_price = 4.98;
s.buy_price = 4.96;
s.buy_quantity = 1000;
s.sell_price = 4.99;
s.sell_quantity = 2000;
stocks_.push_back(s);
// Serialize the data first so we know how large it is.
std::ostringstream archive_stream;
boost::archive::text_oarchive archive(archive_stream);
archive << stocks_;
outbound_data_ = archive_stream.str();
std::cout << "outbound_data_ : " << outbound_data_ << "\n" << std::flush;
std::cout << "outbound_data_.size() : " << outbound_data_.size() << "\n" << std::flush;
// Format the header.
std::ostringstream header_stream;
header_stream << std::setw(header_length) << std::hex << outbound_data_.size();
std::cout << "header_stream.str() : " << header_stream.str() << "\n" << std::flush;
std::cout << "header_stream.str().size() : " << header_stream.str().size() << "\n" << std::flush;
if (!header_stream || header_stream.str().size() != header_length)
{
// Something went wrong, inform the caller.
// boost::system::error_code error(boost::asio::error::invalid_argument);
// socket_.get_io_service().post(boost::bind(handler, error));
return;
}
outbound_header_ = header_stream.str();
std::cout << "outbound_header_ : " << outbound_header_ << "\n" << std::flush;
// Write the serialized data to the socket. We use "gather-write" to send
// both the header and the data in a single write operation.
std::vector<boost::asio::const_buffer> buffers;
buffers.push_back(boost::asio::buffer(outbound_header_));
buffers.push_back(boost::asio::buffer(outbound_data_));
std::size_t sizeSent = asio::write(m_sock, buffers);
std::cout << "sizeSent : " << sizeSent << "\n" << std::flush;
}
std::string receiveResponse() {
std::string response;
/*
asio::streambuf buf;
asio::read_until(m_sock, buf, '\n');
std::istream input(&buf);
std::getline(input, response);
*/
return response;
}
private:
asio::io_service m_ios;
asio::ip::tcp::endpoint m_ep;
asio::ip::tcp::socket m_sock;
enum { header_length = 8 };
std::string outbound_data_;
std::string outbound_header_;
};
int main()
{
const std::string raw_ip_address = "127.0.0.1";
const unsigned short port_num = 3333;
try {
SyncTCPClient client(raw_ip_address, port_num);
// Sync connect.
client.connect();
sleep(1);
std::cout << "Sending request to the server... "
<< std::endl;
std::string response = client.emulateLongComputationOp(10);
std::cout << "Response received: " << response << std::endl;
sleep(100);
std::cout << "\n\n Closing client connection \n\n";
// Close the connection and free resources.
client.close();
}
catch (system::system_error &e) {
std::cout << "Client Error occured! Error code = " << e.code()
<< ". Message: " << e.what();
return e.code().value();
}
return 0;
}
Included File (stocks.hpp)
#ifndef _STOCKS_HPP_
#define _STOCKS_HPP_
struct stock
{
std::string code;
std::string name;
double open_price;
double high_price;
double low_price;
double last_price;
double buy_price;
int buy_quantity;
double sell_price;
int sell_quantity;
template <typename Archive>
void serialize(Archive& ar, const unsigned int version)
{
ar & code;
ar & name;
ar & open_price;
ar & high_price;
ar & low_price;
ar & last_price;
ar & buy_price;
ar & buy_quantity;
ar & sell_price;
ar & sell_quantity;
}
};
#endif
回答1:
You have written Error code = 125. Message: Operation canceled as comment in previous response, i think that socket may be closed before async operation will be done.
What is lifetime of your socket ?
[1] socket is created in Accept method
std::shared_ptr<asio::ip::tcp::socket>
sock(new asio::ip::tcp::socket(m_ios)); // ref count +1
//...
(new Service)->StartHandligClient(sock); // this function returns immediately
// so socket's ref count -1
[2] in StartHandligClient() sock is passed by value, so ref count of socket +1, but
void StartHandligClient(
std::shared_ptr<asio::ip::tcp::socket> sock) { // +1 ref count
read_async_1(sock); // this function returns immediately
return; // -1 ref count of socket
}
[3] in read_async_1 socket is passed by value, +1 on ref count of socket, but this function returns immediately, when function ends, ref count is decreased and socket object is deleted.
You created lambda object to execute asynchronus operation, but socket object may be closed before doing it.
回答2:
You did apparently use a asio::io_service, but you forgot to run it.
m_ios.run();
Run the io_context object's event processing loop.
Fix this and your handler[s] will be called.
You can either create a thread for this, or call it in your main function in your 'main-thread'.
std::thread([this]() { m_ios.run(); } );
Note: Don't forget to stop (1) it later and join the thread (2) if you created one.
来源：https://stackoverflow.com/questions/48128834/boost-asio-async-read-is-not-reading-data-from-the-client